(n.) The continued stem or midrib of a pinnately compound leaf, as in a rose leaf or a fern.
(n.) The principal axis in a raceme, spike, panicle, or corymb.
(n.) The shaft of a feather. The rhachis of the after-shaft, or plumule, is called the hyporhachis.
(n.) The central cord in the stem of a crinoid.
(n.) The median part of the radula of a mollusk.
(n.) A central cord of the ovary of nematodes.
Example Sentences:
(1) Abnormalities found in mutant feathers included decreased overall size, absence of prelumulae and prefiloplumulae feathers, an abnoramlly small rhachis with a disproportionally small medulla, thickening of the feather-sheath, and increased abundance of pulp cells.
Vexillum
Definition:
(n.) A flag or standard.
(n.) A company of troops serving under one standard.
(n.) A banner.
(n.) The sign of the cross.
(n.) The upper petal of a papilionaceous flower; the standard.
(n.) The rhachis and web of a feather taken together; the vane.
Example Sentences:
(1) Small (less than 10 mm) consecutive sections of the byssal threads of Mytilus edulis, M. californianus, Geukensia demissa, Atrina vexillum, and A. rigida were analyzed by amino acid analysis to determine if chemical composition remains constant as a function of location in thread segments.